A Green Synthesis of Graphene-Based Composite for Energy Storage Application

Lim, Jim Hui Kern (2016) A Green Synthesis of Graphene-Based Composite for Energy Storage Application. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Global warming, air-pollution emission, rising oil prices and diminishing supply of fossil fuel have been increasingly driving the world towards the development of clean and environmentally friendly high power energy resources. Energy storage technology appears as one of the most promising options since renewably-generated electrical energy can be stored during the optimum production period for future use. Electrochemical capacitors, also known as supercapacitors, have attracted considerable attention over the past decades owing to their higher power density and longer cycle life and moderate energy density. Innovative electrode material with desirable properties coupled with low cost and sustainability is the key for realizing high-performance supercapacitors. Graphene, a two-dimensional nanosheet of graphite arranged in a honeycomb crystal structure, have been investigated intensively as a promising material candidate for supercapacitor owing to its excellent electrical conductivity, large theoretical surface area, good structural flexibility and superior chemical tolerance. In this study, graphene-molybdenum oxide composite materials were prepared via green synthesis method, hydrothermal and evaluated as supercapacitor electrodes. The morphology and structure of the composite were examined by using Scanning Electron Microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR). The thermal stability of the composite was examined by thermogravimetric-differential scanning calorimetry (TGA-DSC) analysis. The electrochemical performances of the composite were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (CD) method, and electrochemical impedance spectroscopy (EIS). The electrochemical results show that the composite electrodes possess improved specific capacitance of 122 F/g at a scan rate of 5 mV/s, which is about 22% higher that of pure graphene. Additionally, the composite electrodes exhibit good capacitive properties and a high specific energy with superior capacitive retention after 1000 cycles. In contrast to the previously reported systems that are usually complicated and costly, the present work potentially provides a readily scalable technological platform for economic mass production of energy storage devices.